This invention relates to an apparatus and method of filling carbon dioxide (CO.sub.2) cylinders. More particularly, the invention involves filling liquefied CO.sub.2 high pressure cylinders by passing liquefied CO.sub.2 from a low pressure container of liquefied CO.sub.2.
High pressure cylinders for liquefied CO.sub.2 have a single valved port and, by long established practice, are filled at a recharging depot where liquefied CO.sub.2 is pumped into each cylinder through its valved port. Filling is continued until the weight of CO.sub.2 is equal to two-thirds of the weight of water that would fill the cylinder. This customary filling limit serves to provide a safe vapor space above the liquefied CO.sub.2 in the cylinder.
In contrast to the common, laborious and costly practice of transporting each cylinder from a CO.sub.2 user to a depot, filling it while carefully weighing the added CO.sub.2 to avoid overfilling, and transporting the recharged cylinder back to the CO.sub.2 user, the invention provides a system of supplying CO.sub.2 to cylinders much like the familiar delivery of fuel oil to the tanks at several homes. In spite of the extensive distribution of CO.sub.2 cylinders and the frequent need to transport each to a refilling depot and back again to the user, no practical proposal is known for obviating this cumbersome and expensive system of shuttling cylinders between CO.sub.2 customers and a recharging depot.
Accordingly, a principal object of the invention is to provide an apparatus and method for filling cylinders at various locations with liquefied CO.sub.2 from a large container that is transported to the various locations.
Another important object is to provide an apparatus for filling CO.sub.2 cylinders which is simple to install and to use.
A further object is provide apparatus that automatically limits filling cylinders with liquid CO.sub.2 to a selected safe level.
These and other features and advantages of the invention will be apparent from the description which follows.